libuv: fall back to gcc/clang builtins on arm

mingw-w64-libuv/PKGBUILD

@@ -5,7 +5,7 @@ _realname=libuv
 pkgbase=mingw-w64-${_realname}
 pkgname="${MINGW_PACKAGE_PREFIX}-${_realname}"
 pkgver=1.40.0
-pkgrel=2
+pkgrel=3
 pkgdesc="Cross-platform asynchronous I/O (mingw-w64)"
 arch=('any')
 mingw_arch=('mingw32' 'mingw64' 'ucrt64')
@@ -14,11 +14,14 @@ license=("custom")
 makedepends=("${MINGW_PACKAGE_PREFIX}-gcc")
 depends=("${MINGW_PACKAGE_PREFIX}-gcc-libs")
 options=('staticlibs' 'strip')
-source=("${_realname}-${pkgver}.tar.gz"::"https://github.com/libuv/libuv/archive/v${pkgver}.tar.gz")
-sha256sums=('70fe1c9ba4f2c509e8166c0ca2351000237da573bb6c82092339207a9715ba6b')
+source=("${_realname}-${pkgver}.tar.gz"::"https://github.com/libuv/libuv/archive/v${pkgver}.tar.gz"
+        "libuv-win-atomics-non-x86.patch")
+sha256sums=('70fe1c9ba4f2c509e8166c0ca2351000237da573bb6c82092339207a9715ba6b'
+            'cfdc72694fb8578499eece9cf51102b8cc140d2ab07cd77c1a371b950d2add95')
 
 prepare() {
   cd "${srcdir}/${_realname}-${pkgver}"
+  patch -Np1 -i ../libuv-win-atomics-non-x86.patch
  ./autogen.sh
 }
 

mingw-w64-libuv/libuv-win-atomics-non-x86.patch

@@ -0,0 +1,26 @@
+--- libuv-1.40.0/src/win/atomicops-inl.h.orig	2021-01-12 14:43:58.259375600 -0800
++++ libuv-1.40.0/src/win/atomicops-inl.h	2021-01-12 14:49:35.587505100 -0800
+@@ -41,6 +41,8 @@
+ 
+ #else /* GCC */
+ 
++#if defined(__i386__) || defined(__x86_64__)
++
+ /* Mingw-32 version, hopefully this works for 64-bit gcc as well. */
+ static inline char uv__atomic_exchange_set(char volatile* target) {
+   const char one = 1;
+@@ -52,6 +54,14 @@
+   return old_value;
+ }
+ 
++#else
++
++static inline char uv__atomic_exchange_set(char volatile* target) {
++  return __atomic_exchange_n(target, 1, __ATOMIC_SEQ_CST);
++}
++
++#endif
++
+ #endif
+ 
+ #endif /* UV_WIN_ATOMICOPS_INL_H_ */